2 Answers
2

On Linux systems, if Apache has been installed from a package
repository, you must have installed the corresponding Apache "dev"
package as well.

For most Linux distributions, the "dev" package for Apache 2.X is
"apache2-dev" where the corresponding Apache package was "apache2".
Some systems however distinguish the "dev" package based on which MPM
is used by Apache. As such, it may also be called "apache2-worker-dev"
or "apache2-prefork-dev". If using Apache 2.X, do not mix things up
and install "apache-dev" by mistake, which is the "dev" package for
Apache 1.3 called just "apache".

You are missing that dev package for Apache. This is why 'apxs' cannot be found and subsequent issues occur.